Chemical vapor deposition process and coated article

ABSTRACT

A chemical vapor deposition process and coated article are disclosed. The chemical vapor deposition process includes positioning an article in a chemical vapor deposition chamber, then introducing a deposition gas to the chemical vapor deposition chamber at a sub-decomposition temperature that is below the thermal decomposition temperature of the deposition gas, and then heating the chamber to a super-decomposition temperature that is equal to or above the thermal decomposition temperature of the deposition gas resulting in a deposited coating on at least a surface of the article from the introducing of the deposition gas. The chemical vapor deposition process remains within a pressure range of 0.01 psia and 200 psia and/or the deposition gas is dimethylsilane. The coated article includes a substrate subject to corrosion and a deposited coating on the substrate, the deposited coating having silicon, and corrosion resistance.

PRIORITY

The present application claims priority and benefit of U.S. ProvisionalPatent Application No. 62/045,168, entitled CHEMICAL VAPOR DEPOSITIONPROCESS AND COATED ARTICLE, filed on Sep. 3, 2014, the entirety of whichis hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention is directed to a chemical vapor depositionprocess. More particularly, the present invention is directed tochemical vapor deposition processes and articles coated by suchprocesses with deposition at least beginning at a temperature below thethermal decomposition temperature of a deposition gas.

BACKGROUND OF THE INVENTION

Often, surfaces of substrates do not include desired performancecharacteristics. The failure to include specific desired performancecharacteristics can result in surface degradation in certainenvironments, an inability to meet certain performance requirements, orcombinations thereof. For example, in certain environments, metallic,glass, and ceramic surfaces can be subjected to wear and otherundesirable surface activities such as chemical adsorption, catalyticactivity, corrosive attack, oxidation, by-product accumulation orstiction, and/or other undesirable surface activities.

Undesirable surface activities can cause chemisorption of othermolecules, reversible and irreversible physisorption of other molecules,catalytic reactivity with other molecules, attack from foreign species,a molecular breakdown of the surface, physical loss of substrate, orcombinations thereof.

To provide certain desired performance characteristics, a siliconhydride surface and unsaturated hydrocarbon reagents can be reacted inthe presence of a metal catalyst. Such processes suffer from thedrawbacks that complete removal of this catalyst from the treated systemis often difficult and the presence of the catalyst can re-introduceundesirable surface activity. Amorphous silicon-based chemical vapordeposition materials are also susceptible to dissolution by caustic highpH media, thereby limiting their use in such environments.

Chemical vapor deposition has been used to produce coatings withimproved characteristics by depositing a material at a temperature abovethe thermal decomposition temperature of the material. However, furtherimprovements are desired.

A chemical vapor deposition process and coated article that show one ormore improvements in comparison to the prior art would be desirable inthe art.

BRIEF DESCRIPTION OF THE INVENTION

In an embodiment, a chemical vapor deposition process includespositioning an article in a chemical vapor deposition chamber, thenintroducing a deposition gas to the chemical vapor deposition chamber ata sub-decomposition temperature that is below the thermal decompositiontemperature of the deposition gas, and then heating the chamber to asuper-decomposition temperature that is equal to or above the thermaldecomposition temperature of the deposition gas resulting in a depositedcoating on at least a surface of the article from the introducing of thedeposition gas. The chemical vapor deposition process remains within apressure range of 0.01 psia and 200 psia.

In another embodiment, a chemical vapor deposition process includespositioning an article in a chemical vapor deposition chamber, thenintroducing dimethylsilane to the chemical vapor deposition chamber at asub-decomposition temperature that is below the thermal decompositiontemperature of the dimethylsilane in the absence of a catalyst, and thenheating the chamber to a super-decomposition temperature that is equalto or above the thermal decomposition temperature of the dimethylsilaneresulting in a deposited coating on at least a stainless steel surfaceof the article from the introducing of the deposition gas.

In another embodiment, a coated article includes a substrate subject tocorrosion and a deposited coating on the substrate, the depositedcoating having silicon, and one or both of the substrate resistscorrosion with the deposited coating on the substrate when exposed to15% NaClO by a rate of at least 5% greater than the corrosion rate of acoating applied with the same process but without introducing thedeposition gas at the sub-decomposition temperature, and the substratewith the deposited coating has a 15% NaClO corrosion rate of between 0and 3 mils per year.

Other features and advantages of the present invention will be apparentfrom the following more detailed description, taken in conjunction withthe accompanying drawings which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a chemical vapor depositionchamber during a chemical vapor deposition process to form a coatedproduct, according to an embodiment of the disclosure.

FIG. 2 shows a plot of corrosion data for coated products formed bydeposition at various temperatures, then exposed to 15% NaClO, accordingto an embodiment of the disclosure.

FIG. 3 shows a plot of corrosion data for coated products formed bydeposition at various temperatures, then exposed to 6 mol/L HCl,according to an embodiment of the disclosure.

FIG. 4 shows plots for up to eight days of electrochemical impedancespectroscopy for a coated product formed by chemical vapor depositionwith a deposition gas introduced at a temperature below the thermaldecomposition temperature of the deposition gas, according to anembodiment of the disclosure.

FIG. 5 shows plots for up to eight days of electrochemical impedancespectroscopy for a coated product formed by chemical vapor depositionwith a deposition gas introduced at a temperature at or above thethermal decomposition temperature of the deposition gas, according to anembodiment of the disclosure.

Wherever possible, the same reference numbers will be used throughoutthe drawings to represent the same parts.

DETAILED DESCRIPTION OF THE INVENTION

Provided are a chemical vapor deposition processes and articles coatedby such processes. Embodiments of the present disclosure, for example,in comparison to concepts failing to include one or more of the featuresdisclosed herein, permit a reduction in degradation of impedance in saltwater, permit decreased corrosion, permit an increase in density of acoating, permit other suitable features and advantages that will beapparent from the disclosure herein, permit use of a wider variety ofmaterials (for example, materials more prone to oxidation and/or heataffect), permit treatment of hydrogen embrittlement, enhanced sulfurinertness, enhanced dielectric properties (for example, having apolarization-field loop that is linear or substantially linear),enhanced wear resistance, or a combination thereof.

Referring to FIG. 1, in one embodiment, a chemical vapor depositionprocess 100 includes positioning (step 102) an article 101 within achemical vapor deposition chamber 103, then operating (step 104) thechemical vapor deposition chamber 103. The operating of the chemicalvapor deposition chamber 103 includes purging the chemical vapordeposition chamber 103, introducing a deposition gas 111 from acontainer/cylinder 107 to the chemical vapor deposition chamber 103,heating the chemical vapor deposition chamber 103, or a combinationthereof. Throughout the operating, the pressure is adjusted or within arange, for example, of between 0.01 psia and 200 psia, 1.0 psia and 100psia, 5 psia and 40 psia, 1.0 psia, 5 psia, 40 psia, 100 psia, 200 psia,or any suitable combination, sub-combination, range, or sub-rangetherein. As will be appreciated by those skilled in the art, thechemical vapor deposition chamber 103 is capable of being an internaloven region or a vessel within an internal region of an oven.

The positioning (step 102) of the article 101 includes any technique forplacing the article 101 within the chemical vapor deposition chamber103. For example, suitable techniques include, but are not limited to,positioning a plurality of the articles 101 within the chemical vapordeposition chamber 103, positioning a plurality of the articles 101 onor in one or more chemical vapor deposition fixtures that are positionedwithin the chemical vapor deposition chamber 103, positioning only oneof the articles 101 within the chemical vapor deposition chamber 103,and/or cleaning a portion of one or more of the articles 101 prior to orduring positioning within the chemical vapor deposition chamber 103, forexample, to remove debris, dirt, grease, or other non-native substances.

The purging during the operating (step 104) includes selectivelyapplying a purge gas 105 to the chemical vapor deposition chamber 103that evacuated or substantially evacuated. The purge gas 105 isnitrogen, helium, argon, or any other suitable inert gas. The purgingincludes introduction of the purge gas 105 to the chemical vapordeposition chamber 103. The purging is in one purge cycle, two purgecycles, three purge cycles, more than three purge cycles, or anysuitable number of purge cycles that permits chemical vapor depositionchamber 103 to be a chemically inert environment.

After the purging, the operating (step 104) includes the introducingand/or decomposing of the deposition gas 111. Suitable species of thedeposition gas 111 include, but are not limited to, an organosilane,dimethylsilane, any silane gas, or any other suitable chemical vapordeposition gas. Other suitable materials for the introducing and/orsubsequent treatment include, but are not limited to, trimethylsilane,dialkylsilyl dihydride, alkylsilyl trihydride,organofluorotrialkoxysilanes, and/or organofluorosilylhydrides. Infurther embodiments, the deposition gas 111 is devoid ofnitrogen-containing species, such as, an aminosilanes.

The deposition gas 111 is introduced at a sub-decomposition temperaturethat is below the thermal decomposition temperature of the depositiongas 111. As used herein, the phrase “sub-decomposition temperature”refers to conditions at which the deposition gas 111 will not produce acoating of more than 100 Angstroms, is not visually discernible, is notdetectable through infrared testing, or a combination thereof. Dependingupon the species of the deposition gas 111, suitable sub-decompositiontemperatures include, but are not limited to, less than 30° C., lessthan 60° C., less than 100° C., less than 150° C., less than 200° C.,less than 250° C., less than 300° C., less than 350° C., less than 400°C., less than 440° C., less than 450° C., between 100° C. and 300° C.,between 125° C. and 275° C., between 200° C. and 300° C., between 230°C. and 270° C., or any suitable combination, sub-combination, range, orsub-range therein.

In one embodiment, at least during the introducing of the deposition gas111, the operating (step 104) of the chemical vapor deposition chamber103 is substantially devoid of catalyst (for example, being below alevel that impacts the process 100) or devoid of catalyst (for example,being absent at detectable levels and/or being completely absent).

During and/or after the introducing of the deposition gas 111, theoperating (step 104) of the chemical vapor deposition chamber 103includes heating the chemical vapor deposition chamber 103 to asuper-decomposition temperature that is equal to or above the thermaldecomposition temperature of the deposition gas 111 under conditionswithin the chemical vapor deposition chamber 103. As used herein, thephrase “super-decomposition temperature” refers to conditions that willproduce a coating of more than 100 Angstroms, is visually discernible,is detectable through infrared testing, or a combination thereof.

Heating the chemical vapor deposition chamber 103 to thesuper-decomposition temperature in the presence of the deposition gas111 results in a deposited coating 109 on at least a surface 113 of thearticle 101. In one embodiment, the surface 113 is a stainless steelsurface (martensitic or austenitic), a nickel-based alloy, a metalsurface, a metallic surface (ferrous or non-ferrous; tempered ornon-tempered; and/or equiaxed, directionally-solidified, or singlecrystal), a ceramic surface, a ceramic matrix composite surface, a glasssurface, ceramic matrix composite surface, a composite metal surface, acoated surface, a fiber surface, a foil surface, a film, a polymericsurface (such as, polytetrafluoroethylene), and/or any other suitablesurface capable of withstanding operational conditions of the process100.

In further embodiments, one or more constituents of the surface 113 arebelow a concentration value. For example, in some embodiments havingcopper, the concentration value is 5%, 1.2%, 1%, 0.9%, 0.4%, between0.15% and 0.4%, between 0.01% and 1.2%, between 0.03% and 5%, between0.03% and 0.9%, or any suitable combination, sub-combination, range, orsub-range therein. In some embodiments having magnesium, theconcentration value is 3%, 1.5%, 1.2%, between 0.2% and 3%, between0.01% and 2%, between 0.05% and 1.5%, between 0.8% and 1.2%, or anysuitable combination, sub-combination, range, or sub-range therein. Insome embodiments having manganese, the concentration value is 2%, 1.8%,1.5%, 1.4%, 0.15%, between 0.02% and 1.4%, between 0.03% and 1.5%,between 0.05% and 1.8%, between 1% and 1.5%, or any suitablecombination, sub-combination, range, or sub-range therein. In furtherembodiments, the concentration value relates to more than one of theseconstituents, for example, being below a sum of 8.5%, 5.6%, 4.2%, or anysuitable combination, sub-combination, range, or sub-range therein.

The heating of the chemical vapor deposition chamber 103 is at anysuitable heating rate from the sub-decomposition temperature to thesuper-decomposition temperature. Suitable heating rates include, but arenot limited to, between 6° C. per minute and 400° C. per minute, between20° C. per minute and 30° C. per minute, between 20° C. per minute and50° C. per minute, between 50° C. per minute and 100° C. per minute,between 10° C. per minute and 30° C. per minute, greater than 10° C. perminute, greater than 20° C. per minute, greater than 30° C. per minute,greater than 40° C. per minute, greater than 50° C. per minute, greaterthan 100° C. per minute, less than 100° C. per minute, less than 50° C.per minute, less than 40° C. per minute, less than 30° C. per minute,less than 20° C. per minute, at 20° C. per minute, at 30° C. per minute,at 40° C. per minute, at 50° C. per minute, or any suitable combination,sub-combination, range, or sub-range therein. At such rates, in oneembodiment, the heating of the chemical vapor deposition chamber 103 isfor a period of between 3 minutes and 10 minutes, a period of between 5minutes and 10 minutes, a period of between 7 minutes and 10 minutes, aperiod of between 3 minutes and 7 minutes, a period of between 3 minutesand 5 minutes, or any suitable combination, sub-combination, range, orsub-range therein.

Depending upon the species of the deposition gas 111, suitablesuper-decomposition temperatures include, but are not limited to,between 300° C. and 600° C., between 380° C. and 420° C., between 400°C. and 460° C., between 420° C. and 460° C., between 440° C. and 460°C., between 400° C. and 600° C., between 450° C. and 600° C., between500° C. and 600° C., greater than 400° C., greater than 450° C., greaterthan 460° C., greater than 480° C., greater than 500° C., less than 600°C., less than 550° C., less than 500° C., less than 450° C., or anysuitable combination, sub-combination, range, or sub-range therein.

The operating (step 104) includes any other suitable treatments of thearticle 101. Suitable treatments include, but are not limited to,oxidizing of the surface 113 and/or the deposited coating 109,functionalizing of the surface 113 and/or the deposited coating 109, ora combination thereof. In one embodiment, the oxidizing of the surface113 and/or the deposited coating 109 is at an oxidizing temperature toform an oxidized coating (not shown). Depending upon the specificmaterials, oxidizing temperatures include, but are not limited to,between 100° C. and 500° C., between 300° C. and 350° C., between 280°C. and 320° C., between 440° C. and 460° C., or any suitablecombination, sub-combination, range, or sub-range therein. In oneembodiment, the functionalizing of the surface 113 and/or the depositedcoating 109 is by introducing trimethylsilane.

The deposited coating 109 includes properties corresponding withparameters of the operating (step 104). For example, the depositedcoating 109 has corrosion and impedance properties based upon theoperating (step 104) of the chemical vapor deposition chamber 103 duringthe process 100. Suitable thicknesses of the deposited coating 109include, but are not limited to, between 100 nm and 10,000 nm, between200 nm and 5,000 nm, between 300 nm and 1,500 nm, between 150 Angstromsand 450 Angstroms, between 350 Angstroms and 450 Angstroms, greater than100 Angstroms, greater than 200 Angstroms, greater than 300, greaterthan 400 Angstroms, Angstroms greater than 450 Angstroms, or anysuitable combination, sub-combination, range, or sub-range therein.

In one embodiment, the corrosion properties of the deposited coating 109resist 15% NaClO substantially longer than a comparative coating appliedby deposition at or above the thermal decomposition temperature of thedecomposition gas 111. For example, as is shown in FIG. 2 and furtherdescribed with reference to Example 1, embodiments of the article 101having the deposited coating 109 formed by the process 100 result indecreased corrosion rates 201 (for example, in mils per year) that aredecreased, for example, from between 5% and 10% of the corrosion rate203 for deposition at a thermal decomposition temperature 205 (forexample, in degrees C.) of the deposition gas 111. Likewise, embodimentsof the article 101 having the deposited coating 109 formed by theprocess 100 result in the decreased corrosion rates 201 being lower bybetween 8 mils per year and 17 mils per year in comparison to thecorrosion rate for the comparative coating formed by deposition at orabove the thermal decomposition temperature 205 of the deposition gas111. In various embodiments, the corrosion resistance to 15% NaClO isbetween 0 and 3 mils per year, 0 and 2 mils per year, 0 and 1 mil peryear, 1 mil per year, 2 mils per year, 3 mils per year, or any suitablecombination, sub-combination, range, or sub-range therein.

In one embodiment, the corrosion properties of the deposited coating 109resist 6M HCl longer than the comparative coating formed by depositionat or above the thermal decomposition temperature 305 of thedecomposition gas 111. For example, as is shown in FIG. 3 and furtherdescribed with reference to Example 2, embodiments of the article 101having the deposited coating 109 formed by the process 100 result in adecreased corrosion rate 301 (for example, in mils per year) beingbetween 60% and 90% of the corrosion rate 303 for the comparativecoating formed by deposition at or above the thermal decompositiontemperature 305 (for example, in degrees C.) of the deposition gas 111.Likewise, embodiments of the article 101 having the deposited coating109 formed by the process 100 result in a decreased corrosion rate beinglower by between 0.5 mils per year and 3 mils per year in comparison tothe corrosion rate for deposition at the thermal decompositiontemperature of the deposition gas 111. In various embodiments, thecorrosion resistance to 6M HCl is between 0 and 0.5 mils per year, 1 and1.5 mils per year, 1.5 and 2.5 mils per year, 2.5 and 3 mils per year, 2and 3 mils per year, 2.5 and 3.5 mils per year, or any suitablecombination, sub-combination, range, or sub-range therein.

In one embodiment, the impedance properties (quantitativelyrepresentative of impermeability) of the deposited coating 109 includedecreased degradation of impedance in comparison to the comparativecoating formed by deposition at or above the thermal decompositiontemperature of the decomposition gas 111. For example, as is shown inFIGS. 4-5 and further described with reference to Example 3, embodimentsof the article 101 having the deposited coating 109 formed by theprocess 100 result in less degradation of impedance over an eight-dayperiod of salt water exposure as illustrated by electrochemicalimpedance spectroscopy. In one embodiment, impedance of the depositedcoating 109 increases after an initial degradation, for example, afterone day, indicative of self-passivation.

Referring to FIG. 4, in one embodiment, impedance 401 (in ohms) of thedeposited coating 109 is substantially linear over a frequency 403, forexample, of between 100 Hz and 100,000 Hz, independent of the exposureto the salt water. The impedance 401 at frequencies of less than 100 Hzshows discernible degradation, but substantially less degradation thanthe comparative impedance 501 (in ohms) of the comparative coating (seeFIG. 5).

In one embodiment, the degradation of the deposited coating 109 duringthe eight-day period and/or smaller periods within (for example, one dayor six days) is less than 1 MOhm. In further embodiments, thedegradation is less than 0.9 MOhm, less than 0.7 MOhm, less than 0.6MOhm, between 0.5 MOhm and 0.9 MOhm, at 0.872 MOhm, at 0.659 MOhm, at0.556 MOhm, or any suitable combination, sub-combination, range, orsub-range therein. Additionally or alternatively, in one embodiment, thedegradation of the deposited coating 109 is less than 30%. In furtherembodiments, the degradation is less than 23%, less than 20%, between18% and 30%, between 20% and 30%, between 18% and 23%, at 29%, at 22%,at 19%, or any suitable combination, sub-combination, range, orsub-range therein.

In one embodiment, the difference in the degradation of the depositedcoating 109 compared to the degradation of the comparative coatingformed by deposition at or above the thermal decomposition temperatureof the decomposition gas 111 over the same period of exposure to saltwater is greater than 0.7 MOhm. In further embodiments, the differenceis greater than 1 MOhm, greater than 2 MOhm, between 0.7 MOhm and 2.2MOhm, between 2 MOhm and 2.2 MOhm, between 0.7 MOhm and 2.1 MOhm, at0.762 MOhm, at 2.007 MOhm, at 2.166 MOhm, or any suitable combination,sub-combination, range, or sub-range therein. Additionally oralternatively, in one embodiment, the differences in the degradation ofthe deposited coating 109 compared to the degradation of the comparativecoating formed by deposition at or above the thermal decompositiontemperature of the decomposition gas 111 over the same period ofexposure to salt water is greater than 45%, greater than 75%, greaterthan 79%, between 45% and 80%, between 45% and 76%, between 75% and 80%,at 46.63%, at 75.28%, at 79.57%, or any suitable combination,sub-combination, range, or sub-range therein.

EXAMPLES

In a first example, corrosion resistance of the deposited coating 109 istested by applying 15% NAClO to various embodiments of the depositedcoating 109 formed by introducing of dimethylsilane as the depositiongas 111 and comparing to a comparative coating formed by deposition atthe thermal decomposition temperature of the decomposition gas 111,which is 450°.

As is shown in FIG. 2, the corrosion properties of the deposited coating109 resist 15% NaClO substantially longer than the comparative coating203. For example, the comparative coating 203 has a corrosion rate ofbetween 9 mils per year and 18 mils per year, while all embodiments ofthe deposited coating have the decreased corrosion rates 201 of lessthan 1 mil per year.

Specifically, the corrosion rate of the embodiment with thesub-decomposition temperature being at 27° C. is between 0 and 0.2 milsper year. The corrosion rate of the embodiment with thesub-decomposition temperature being at 100° C. is between 0 and 0.5 milsper year. The corrosion rate of the embodiment with thesub-decomposition temperature being at 250° C. is between 0.2 and 0.5mils per year. The corrosion rate of the embodiment with thesub-decomposition temperature being at 300° C. is between 0.1 and 0.3mils per year. The corrosion rate of the embodiment with thesub-decomposition temperature being at 350° C. is between 0.2 and 0.4mils per year. The corrosion rate of the embodiment with thesub-decomposition temperature being at 400° C. is between 0.2 and 0.4mils per year.

In a second example, corrosion resistance of the deposited coating 109is tested by applying 6M HCl to the deposited coating 109. As is shownin FIG. 3, the corrosion properties of the deposited coating 109 resist6M HCl equal to or longer than the comparative coating. For example, thecomparative coating has the corrosion rate 303 of between 0.5 mils peryear and 5 mils per year, while all embodiments of the deposited coatinghave the decreased corrosion rates 301 of less than 3.5 mils per year.

Specifically, the corrosion rate of the embodiment with thesub-decomposition temperature being at 27° C. is between 1 and 1.5 milsper year. The corrosion rate of the embodiment with thesub-decomposition temperature being at 100° C. is between 1.75 and 2mils per year. The corrosion rate of the embodiment with thesub-decomposition temperature being at 250° C. is between 0.4 and 0.6mils per year. The corrosion rate of the embodiment with thesub-decomposition temperature being at 300° C. is between 2.5 and 3 milsper year. The corrosion rate of the embodiment with thesub-decomposition temperature being at 350° C. is between 2.2 and 2.9mils per year. The corrosion rate of the embodiment with thesub-decomposition temperature being at 400° C. is between 2.5 and 3.5mils per year.

In a third example, impedance properties of the deposited coating 109are tested by electrochemical impedance spectroscopy. As is shown bycomparing FIG. 4, corresponding to an embodiment of the depositedcoating 109, and FIG. 5, corresponding to the comparative coating, thedeposited coating 109 has substantially decreased degradation ofimpedance in comparison to the comparative coating. For example, theimpedance 401 at frequencies of less than 100 Hz shows discernibledegradation, but substantially less degradation than the comparativeimpedance 501 of the comparative coating.

Specifically, referring to FIG. 4, the degradation of the depositedcoating 109 during an eight-day period is 0.872 MOhm over one day, 0.659MOhm over six days, and 0.556 MOhm over eight days, based uponmeasurements of 2.988 MOhm at zero days 405, 2.116 MOhm at one day 407,2.329 MOhm at six days 409, and 2.432 MOhm at eight days 411. Incomparison, referring to FIG. 5, the degradation of the comparativecoating during an eight-day period is 1.634 MOhm over one day, 2.666MOhm over six days, and 2.722 MOhm over eight days, based uponmeasurements of 2.822 MOhm at zero days 503, 1.188 MOhm at one day 505,0.156 MOhm at six days 507, and 0.100 MOhm at eight days 509.

While the invention has been described with reference to one or moreembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims. In addition, all numerical values identified in the detaileddescription shall be interpreted as though the precise and approximatevalues are both expressly identified.

What is claimed is:
 1. A chemical vapor deposition process, comprising:positioning an article in a chemical vapor deposition chamber; thenpurging and evacuating the chemical vapor deposition chamber; thenintroducing a deposition gas to the chemical vapor deposition chamber ata sub-decomposition temperature that is below the thermal decompositiontemperature of the deposition gas; and then heating the chamber to asuper-decomposition temperature that is equal to or above the thermaldecomposition temperature of the deposition gas resulting in a depositedcoating on at least a surface of the article from the introducing of thedeposition gas; wherein the chemical vapor deposition process remainswithin a pressure range of 0.01 psia and 200 psia, wherein thedeposition gas is selected from the group consisting of an organosilane,dimethylsilane and a silane gas.
 2. The process of claim 1, wherein thesub-decomposition temperature is between 100° C. and 450° C.
 3. Theprocess of claim 1, wherein the sub-decomposition temperature is between100° C. and 300° C.
 4. The process of claim 1, wherein the heating ofthe chamber heats from the sub-decomposition temperature to thesuper-decomposition temperature at a rate of between 6° C. per minuteand 10° C. per minute.
 5. The process of claim 1, wherein the thermaldecomposition temperature is between 440° C. and 460° C.
 6. The processof claim 1, wherein the super-decomposition temperature is greater than440° C.
 7. The process of claim 1, wherein the chemical vapor depositionchamber is substantially devoid of catalyst during the introducing ofthe deposition gas.
 8. The process of claim 1, wherein the chemicalvapor deposition chamber is devoid of catalyst during the introducing ofthe deposition gas.
 9. The process of claim 1, wherein the surface is astainless steel surface.
 10. The process of claim 1, wherein the surfaceis a nickel-based alloy.
 11. The process of claim 1, further comprisingoxidizing the deposited coating at an oxidizing temperature of between300° C. and 350° C. to form an oxidized coating.
 12. The process ofclaim 11, further comprising functionalizing the oxidized coating byintroducing trimethylsilane to the deposited coating at afunctionalizing temperature of between 400° C. and 500° C.
 13. Theprocess of claim 1, wherein the deposited coating resists corrosion whenexposed to 15% NaClO by a rate of at least 5% greater, in mils per year,than the corrosion rate of a coating applied with the same process butwithout introducing the deposition gas at the sub-decompositiontemperature.
 14. The process of claim 1, wherein the deposited coatinghas a 15% NaClO corrosion rate of between 0 and 3 mils per year.